This invention relates generally to fluid jet nozzles and more particularly to a flow sensor located in a chamber downstream of the orifice to sense the flow characteristics of the fluid jet, and the condition of the nozzle orifice.
In fluid jet cutters and cleaners, the condition of the nozzle assembly makes a considerable difference in the quality of fluid jet being produced. The more coherent the stream, in general, the more effective and efficient will be the cutting ability of the stream.
Previously, many different ways were used to monitor the condition of the nozzle. These include visual inspection of the fluid jet stream, measuring the vibrational frequency of the fluid jet, monitoring the noise produced by the fluid jet and measuring the dimensions of the cut and surface finish of the surface cut left by the fluid jet. These methods are often imprecise, expensive or left open to operator skill and opinion.
Other ways to monitor the condition of the nozzle include direct inspection of the nozzle orifice and measuring the weight of the nozzle structure. In order to implement the these systems, the fluid jet has to be stopped and the nozzle removed. Also, considerable damage can be done to the parts being cut prior to discovery of the defective orifice.
Abrasive fluid jet cutters and cleaners are an especially difficult to monitor since the flow characteristics of the fluid jet downstream of the funnel tube can be affected not only by the condition of the orifice and specifics of the fluid jet adjacent the orifice, but also by the configuration and dimensions of the chamber and funnel tube and the type and amount of abrasives being used. Monitoring whether the fluid jet is within permissible limits and causes of the flow abnormalities in the fluid jet is therefore difficult.
The foregoing illustrates limitations known to exist in present fluid jet cutter and cleaning systems. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.